As is known in the art, antenna elements (or more simply “elements”) constituting a phased array antenna have used electric dipoles, for example half-wave dipoles, or coupling slots to transfer energy from a travelling wave within a waveguide mode into the slot and, thereafter, to free space. A topologically deformed version of the half-wave dipole is a patch antenna element having a thin circular plate standing off one-quarter-wavelength (including intervening dielectric materials) from a reflecting plate. The circular plate can be energized by providing radio frequency (RF) signals to multiple input ports. The phase relationship between the ports determines whether a linearly polarized, elliptically polarized, or circularly polarized electromagnetic signal or wave is launched from the plate.
The patch antenna element has a low dimensional profile, but the thinness of the circular plate has a limiting electric field due to edge enhancement effects, even if contoured Rogowski surfaces are used.
Slotted arrays using waveguide must cope with the physical dimensions of the waveguide itself. Since the entire generated power must exist in the waveguide at some point, the waveguide must be insulated (e.g. by creating a vacuum in the waveguide) to prevent breakdown of the extremely high waveguide fields (i.e., high power) within the waveguide. Thus vacuum pumps must be included as part of the system design.
Hence, a need exists for an antenna element that coherently combines the RF outputs from multiple sources and radiates at high peak power levels without inducing air breakdown at an antenna aperture.